The white bumps on a right whale 's head are skin abrasions called callosities .
白色的隆起物在一条脊美鲸的头部是皮肤磨损称为老茧皮。
by the callosities of his forefinger and thumb , by his expression , by his shirt-cuffs
大拇指与食指之间的茧子、表情、衬衣袖口等等，
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